The management of biological samples is a highly complex task due to the multitude of operational steps and the multitude of procedural and security aspects that have to be considered ahead of the execution of each working step. Currently, many of those working steps are executed manually, resulting in prolonged sample processing workflows and an increased risk of erroneous analysis results. The risk of an accidental contact of the lab personnel with the potentially infectious content of biological samples should also be mentioned in this context.
Biological samples, such as tissues, blood, saliva or urine samples are routinely taken from patients by medical personnel in hospitals or in a doctor's practice. They are used for various analyses. Analyses are laboratory procedures determining, for example, the glucose, Fe2+, haematocrite, kreatinine or leukocyte level of the blood or other types of samples. The concentration values obtained from those analyses are important aids in the diagnosis of diseases and are important indicators of the state of health of a patient.
Usually, a sample taken from the patient or laboratory animal provides enough material for multiple analyses. This ensures that a patient does not have to appear a second time and provide an additional blood sample in case an analysis fails or has for other reasons to be repeated, e.g. in case the doctor considers additional diagnostic tests as necessary. For those reasons, a biological sample is usually aliquoted and stored under conditions extending the stability and storage life of the biological sample as long as possible. The process of sample aliquotation yields small sample volumes which can be directly used for analysis.
The storage conditions prolonging the storage life of biological samples usually comprise a low temperature level, e.g. some degrees centigrade above freezing temperature in a refrigerator or even lower temperatures as provided by a freezer.
If a particular analysis has to be executed on a sample, e.g. an analysis determining the glucose level of a blood sample of a patient, the blood sample or an aliquot of the blood sample of that patient has to be taken from the storage device to the biomedical analyzer in which the analysis shall be exercised. The results generated by the analysis are returned to the medical personnel and are used, for example, to determine the status of health of a patient or to monitor the effects of a medical treatment or medication on the patient.
Currently, many of the tasks mentioned beforehand have to be executed manually. The blood sample is aliquoted by a lab professional into smaller samples and manually labeled with the date and time of sample preparation and with an identifier enabling the association of the sample with a particular patient, e.g. a bar code label or a hand written patient number and sampling time written onto the sample. The samples are transferred manually to the storage device. In case an analysis is to be executed on an already stored sample to determine a particular analyte e.g. in the blood of a patient, the lab personnel has to identify the appropriate sample in the storage device manually, has to decap or otherwise pre-process the sample, and has to transfer it to the analyzer.
Multiple sources of errors exist according to said scenario: the lab personnel may have labeled the sample erroneously, may have taken a wrong sample belonging to a different patient for analysis out of the storage or may have used a sample for analysis although the storage duration of that sample was too long to guarantee valid analysis results. In addition, each interaction of a human with a biological sample can be considered as security risk as a sample may have been derived from a patient having an infectious disease.
The use of a sample being too old to apply a particular analysis can have fatal consequences: if the analysis results obtained are wrong due to the age of the sample, wrong analysis results may be obtained resulting in an inappropriate diagnosis or treatment of a patient. The lab personnel therefore has to guarantee somehow that the storage duration of the sample given the storage conditions still enable the retrieval of valid analysis results on that sample and, if not, that said sample is not used for analysis.
Currently, samples are therefore discarded after a predetermined period of time, e.g. one or two weeks, or according to the decision of each individual lab worker applying rules of thumb. The disposal of biological samples according to said rules shall ensure that all stored samples can be used for analysis and that the validity of the analysis result is not negatively affected by the age of the samples. This ‘solution’ is connected with several significant disadvantages: the maximum possible storage duration of a sample still allowing the retrieval of valid results by an analysis depends not only on the storage length and storage conditions but also on the sample type (blood, urine) and the kind of analysis to be performed (the type and property of the analyte to be characterized, e.g. the concentration of glucose, lactate or Troponin-T). The disposal of samples after a fixed period of storage time after which the samples are too old for a particular analysis therefore may lead to a disposal of samples which are still usable for some other kinds of analysis. This solution cannot be considered as optimal, as samples which could have been used for other types of analyses are disposed and more samples have to be taken from the patient as necessary. This results in increased costs, because the patient has to arrange an additional appointment at the hospital, where a new sample, e.g. a blood sample, is taken, because more waste is produced than necessary by disposing samples that could have still be usable for some analyses, and because the lab personnel has additional work with sampling, preprocessing and storing the new samples. The manual disposal of samples after a fixed period of time is very time consuming: in most biomedical laboratories, a multitude of samples is taken from patients, labeled and stored appropriately every day. In case the laboratory supervisor instructs the lab personnel to discards all samples being older than one week to ensure that older samples cannot be used for an analysis requiring a sample age of at the maximum 7 days, the lab personnel may check the age of all stored samples e.g. once a week every Friday. The problem arises that a sample having been taken from a patient on Monday in a particular week will not be disposed during the manual check of sample age executed on Friday of the same week, but will have expired on Monday the next week. As the next manual check of the sample age will be executed on Friday the next week, there is the danger that an analysis request submitted Tuesday, Wednesday or Thursday in the next week will be executed on an old sample resulting in a wrong analysis result. In order to guarantee that this scenario does not happen, the manual examination of the sample age has to be executed much more frequently than the maximum storage time of a sample, e.g. on a daily basis. Another solution is to manually check the sample age of each sample for every individual analysis request on a sample. Both described solutions are current methods in many biomedical laboratories, but both are highly time consuming and error prone.
In the context of biomedical research, an analysis is a technical procedure to characterize the parameter of a biological sample or of an analyte of the sample. The characterization of a parameter of a sample comprises, for example, the determination of the concentration of particular proteins, metabolites, ions or molecules of various sizes in biological samples derived from humans or laboratory animals. The gathered information can be used to evaluate e.g. the impact of the administration of drugs on the organism or on particular tissues. Further analyses may determine optical, electrochemical or other parameters of the samples or the analytes comprised in a sample.
Various analyzers are known for analyzing biological samples in-vitro providing the lab professionals with means to automate some of the above mentioned tasks. One such analyzer, for example, stores for each reagent used a predetermined period of time ranging from the opening of a reagent vessel to the deterioration of the reagent. A reagent is the substance used in an analysis to detect or otherwise characterize an analyte of a sample. The analyzer judges whether a calibration curve factor for a reagent set is applicable or not to another reagent set of the analyzer with the same production number based on the predetermined period of time from the reagent vessel unsealing to the expiration date of the reagent. Another such automatic analyzer is operable to change reagents during analysis without stopping the analysis in the event that a reagent shortage occurs during the analysis. A reagent is transferred from a reagent storage unit to a reagent changing mechanism. Then, the reagent changing mechanism is moved so that reagents are changed.
Such analyzers automate and improve some singular steps of the analysis process chain of a biological sample, e.g. the task of allocating a reagent required for an analysis, thereby taking into consideration the expiration date, the opening of the reagent vessel or the amount of reagent still available in the reagent lot of an analyzer. The prior art, however, does not address the fact that the stability of biological samples is often even more time critical than the expiration date of the reagent. While various buffers and detection reagents may have a storage life of month or even years, the storage life of biological samples is often considerably shorter. Depending on the biological sample and on the analysis to be performed on the sample, the time window within which an analysis can be performed on the sample is often measured in few days given optimal storage conditions.
Prior art systems are not capable of considering the impact of the storage life of a biological sample on the question if an analysis can still be applied on the sample. In particular, they do not address the problem that the maximum acceptable storage life for performing an analysis on a sample does not only depend on the storage time, but also on the type of analysis to be executed on the sample.